To be a bit picky here, a SAN is just the storage network (such as fiber channel) and is often made highly redundant by having two fabrics, multiple switches / ports, and multiple HBA connections. The storage itself is typically referred to as a storage array and is made redundant with multiple controllers and N+1 supporting hardware (fans, power supplies, etc.).
It sounds like what you're really angling for is a logical pool of storage across both sites, which is typically a use case for EMC VPLEX. This carries its own hefty bag of caveats, but will virtualize the storage layer (so to speak) so that the LUN can be presented from both sites without vSphere being aware of it. Alternatively, you can leverage two storage arrays and a replication product such as Zerto, which does offer the ability to take a large majority of the "manual intervention" you list as a requirement out of the equation.